(a) Field of the Invention
The present invention relates to an apochromat grade of objective lens system for microscopes designed for a magnification level of 60.times. and an NA of 1.4.
(b) Description of the Prior Art
As a conventional example of an objective lens system for microscopes which is relatively similar to that according to the present invention, we can mention the one disclosed by U.S. Pat. No. 3,700,311. This objective lens system for microscopes is designed for a magnification level on the order of 100.times., and similar to that according to the present invention in two points: that it adopts an embed doublet (a doublet comprising a lens element embedded in an end surface of another lens element having a larger diameter in the vicinity of the optical axis) as the first lens component and that it selects that Gauss type of lens composition for the image side of said lens system. However, this lens system is designed for NA of 1.3 and comprises eight lens components which have numerous surfaces in contact with air and degrade image contrast. Further, this objective lens system for microscopes is designed for infinite distance (to form an object image at infinite diatance).